Advanced Se₃P₄@C Anode with Exceptional Cycling Life for High Performance Potassium‐Ion Batteries

Abstract Potassium‐ion batteries have attracted increasing attention for next‐generation energy storage systems due to their high energy density and abundance of potassium. However, the lack of suitable anode highly hampers its practical application due to the large ionic radius of K⁺. Herein, a Se₃P₄@mesoporous carbon (Se₃P₄@C) composite is reported as a high‐performance anode for potassium‐ion batteries. The Se₃P₄@C composite is synthesized through an in situ combination reaction between red phosphorus and Se within a porous carbon matrix. In this way, the nano‐sized Se₃P₄ is well confined in the porous carbon and thus exhibits a close contact with the carbon matrix. This can significantly improve the conductivity and alleviate the volume change during the cycling process. As a result, the Se₃P₄@C exhibits a high reversible initial capacity of 1036.8 mAh g⁻¹ at a current density of 50 mA g⁻¹ as well as an excellent cycle performance with a capacity decay of 0.07% per cycle over 300 cycles under 1000 mA g⁻¹. In terms of high specific capacity and stable cycling performance, the Se₃P₄@C anode is a promising candidate for advanced potassium‐ion batteries.